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Figure 1. Sequential production of paraxanthine and 7-methylxanthine from caffeine by E. coli strain MBM019. Price per gram of each compound is based on the lowest retail values found from Sigma Aldrich (March 2022).
Figure 2. N -demethylation of caffeine (red; ▲) to paraxanthine (light grey; ♦) and 7-methylxanthine (dark grey; ■) byE. coli strain MBM019. The supernatant from Round 1 was mixed with fresh MBM019 cells to continue the conversion of caffeine. This process was repeated until nearly complete conversion of caffeine to paraxanthine and 7-methylxanthine was achieved at the end of Round 4. Mean concentrations and standard deviations of triplicate results are shown.
Figure 3. Direct comparison of conversion of caffeine (red) to paraxanthine (light grey) and paraxanthine to 7-methylxanthine (dark grey) by the genetically engineered E. coli strain MBM019. Hatching indicates the concentration of substrate consumed. Solid coloring indicates the concentration of product generated. Substrates for each reaction are also listed at the bottom of the graph. Reactions were conducted at a 2 mL volume in 50 mM KPi with cells at an OD600 of 5 and substrate concentrations of 1 mM. Reaction conditions were set to 37℃, 200 rpm for 5 hours. Mean concentrations and standard deviations of triplicate results are shown from the conclusion of a five-hour resting cell assay.